Cytogenetic findings in an effusion secondary from pleural mesothelioma

[Correlation between sensitivity of the cytogenetic and cytological analysis and thoracoscopic findings in the study of malignant pleural effusions]

We studied 104 patients with pleural effusion. All underwent thoracoscopic exploration to allow direct examination of any pleural lesions present. At the same time pleural biopsies for histopathologic study and samples of pleural fluid for cytopathologic and cytogenetic study were taken. The volume of fluid in pleural cavity was also measured. The aims of the study were: a) to evaluate the sensitivity of cytogenetic analysis and cytopathology, both separately and together, and b) to look for a correlation between the sensitivity of these cell studies and the following thoracoscopic findings: tissue biopsy of pleural neoplasms, volume of pleural effusion and extension of neoplastic lesions in the pleural cavity. Seventeen of the pleural liquids studied were benign and 87 were neoplastic. Cytopathology was sensitive in 55% of the neoplastic cases and cytogenetic study was sensitive in 49%. Sensitivity rose to 74% when both techniques were applied. Cytogenetic study yielded a higher percentage of correct diagnoses in the group with hematologic neoplasia, whereas cytopathology was correct more often in cases of solid tumors, though these differences were not statistically significant. Use of both techniques resulted in correct diagnosis in 92% of patients with mesotheliomas. The number or correct diagnoses achieved with cytopathology tended to increase with size of macroscopic pleural lesion whereas cytogenetic study was more sensitive in patients with minimal or incipient pleural involvement. There were no statistically significant differences in sensitivity of cytopathology and cytogenetic analysis with regard to volume of pleural effusion.

Deletion mapping of the short arm of chromosome 3 in human malignant mesothelioma

Previous cytogenetic investigations have revealed frequent deletions and other unbalanced structural rearrangements of 3p in human malignant mesothelioma. We have performed a restriction fragment length polymorphism analysis by using the polymerase chain reaction and primer sets for seven DNA markers to examine loss of heterozygosity (LOH) from 3p in 25 malignant mesotheliomas. Among 24 cases informative at one or more 3p loci, 15 (62.5%) exhibited LOH with at least one marker. Deletion mapping in these tumors indicates that the common region of chromosomal loss resides within band 3p21, in the vicinity of the D3F15S2 locus. These results suggest that allelic loss from 3p21 is a frequent occurrence in malignant mesothelioma and that one or more putative tumor suppressor genes at this site contribute to the pathogenesis of this malignancy.

Karyotypic changes in the preclinical and subsequent stages of malignant mesothelioma: a case report

The karyotypic evolution was evaluated in cells from recurring pleural effusions in a patient previously exposed to asbestos. Pleural malignant mesothelioma (MM) was diagnosed 4 years after the first cytogenetic examination. The primary cytogenetic changes consisted of loss of chromosomes 1p,14,21, Y, both 22, and derivative chromosomes involving 1, 2, and 14. The modal chromosome number was 44. Sixty-seven percent of the cells had a normal karyotype. After 4 years of spontaneous remission, only 6% of the cells had a normal karyotype, 42% had the same karyotypic changes as found previously, whereas 52% had additional derivative chromosomes involving chromosomes 1, 3, 5, 7, 8, and 12, trisomy 7, 7p, and 11, and partial or whole monosomy 3, 8, and 9. The chromosomal changes are in agreement with the main findings in previous reports. The karyotype remained quite stable for 7 months in vitro. After 23 months in culture, all the cells were near-triploid. Cells established in culture were cytokeratin positive. All derivative and marker chromosomes identified in the cultured cells had previously been observed in direct preparations from the pleural effusions. We conclude that chromosomes 1, 14, 21, and 22 may be involved in the preclinical stage of development of asbestos-induced mesothelioma, whereas the later chromosomal changes may be related to progression of the tumor.

del(6q) as a possible primary change in malignant mesothelioma

Detailed cytogenetic and fluorescence in situ hybridization analysis of an untreated pleural malignant mesothelioma revealed two clonal cell populations, both with a single abnormality affecting chromosome 6. The majority of cells had a deletion together with an inversion of the long arm of chromosome 6, while a smaller population showed loss of this chromosome. The normal 6 was retained. Most reports show that mesotheliomas are characterized by complex karyotypes, involving numerous chromosomes. Abnormalities of chromosome 6 (particularly deletions of the long arm) are among the consistent changes. Our case apparently is the first report of a mesothelioma with a single change involving chromosome 6, which could be the primary cytogenetic change.

Possible cellular and molecular mechanisms for asbestos carcinogenicity

Asbestos fibers may exert their carcinogenic effects on mesothelial cells and bronchial epithelial cells by direct and indirect mechanisms. Direct effects can occur following the physical interaction of fibers with target cells or by the generation of free radicals from the fiber surface; indirect effects, following the interaction of fibers with inflammatory cells can result in the production of cellular mediators such as cytokines and various reactive oxygen species. As a result, target cells may be induced to proliferate and/or sustain genetic alterations, which lead to tumor development.

Establishment and characterization of five human malignant mesothelioma cell lines derived from pleural effusions

Malignant mesothelioma (MM) is an aggressive tumour of the serosal cavities which is associated with exposure to asbestos. Studies of this tumour have been limited by a paucity of well-characterized human MM cell lines. In this study, 5 human MM cell lines were established from pleural effusions of patients with this malignancy. All 5 patients were males with known crocidolite asbestos exposure, who had received no treatment for their disease and in whom the diagnosis was confirmed by cytology, histology and electron microscopy (EM). These lines have been in culture from 11 to 25 months, and all of them for more than 18 passages. The appearance of the cells in culture was extremely varied; in 3 of the lines they were spindle-shaped with few vacuoles (JU77, LO68 and ONE58); in 1 line they had a thick, stellate shape with vacuoles (NO36) and in 1 they were very pleomorphic in both shape and size with irregular membranes and numerous vacuoles [DeH128 (M)]. Upon reaching confluence, cells in 3 of the 5 lines assumed the cobblestone-like pattern characteristic of epithelial-type cells, whereas in the other 2 (LO68 and ONE58) they remained spindle-shaped. All 5 lines demonstrated a loss of contact inhibition (i.e., piling) at confluence. Minimum doubling times varied significantly from 18 hr (JU77) to more than 30 hr [DeH128 (M)]. Cytological examination showed characteristic mesothelial/mesothelioma morphology, and epithelial membrane antigen (EMA) and cytokeratin were demonstrated in cells from all 5 lines. These cells lacked CEA and epithelial mucin. The presence of cell junctions, glycogen and numerous long, thin, branching microvilli was readily demonstrable by EM. All lines had abnormal karyotypes, with the modal chromosome number varying from 40 to 80. Variable chromosome numbers, numerous structural rearrangements and unrecognizable marker chromosomes were readily observed; however, the only consistent change seen was del 6q21 in 4 of the 5 lines. The establishment of these 5 cultured human MM cell lines now provides an opportunity for comparative study of several aspects of the biology of MM in vitro as well as screening new treatment modalities.

Cytogenetic analysis of malignant mesothelioma

Cytogenetic analyses of 40 confirmed malignant mesotheliomas (MMs) are reported. Pleural effusion cells were studied in 90% of the cases by direct method or after culture or both. Biopsy and ascites fluid were also analyzed in some patients. A normal karyotype was found in nine cases, and complex karyotypic abnormalities were observed in 30 cases. In one case, analyzable metaphases were not obtained. The chromosomal changes were all complex and heterogeneous; no consistent presumably specific abnormality was detected. Nevertheless, two main patterns of nonrandom abnormalities were observed: 1) loss of chromosomes 4 and 22, 9p, and 3p in the most of the abnormal cases and corresponding to a hypodiploid and/or hypotetraploid modal chromosome number; and 2) gain of chromosomes 7, 5, and 20 with deletion or rearrangement of 3p as well in the hyperdiploid cases, which were a minority in our series. These findings are discussed in view of other reported cytogenetic studies of MM, asbestos exposure, and possible mechanisms of malignant transformation.

Involvement of 9p in metastatic ovarian adenocarcinomas

By a direct method and after in vitro culture, we cytogenetically analyzed five ovarian adenocarcinomas, using six samples of ascitic fluid. The structural aberrations included rearrangements of chromosomes 1 and 3, in agreement with the results of other researchers. The long arm of chromosome 6 was rearranged in three samples, but no translocation t(6;14) was found. Rearrangements involving 9p were present in all cases, with breakpoints at p13 or p22-23.

Chromosome aberrations in metastatic ovarian cancer: relationship with abnormalities in primary tumors

Twenty malignant effusions secondary to ovarian cancer have been cytogenetically analyzed directly and after short in vitro culture. With the exception of one sample characterized by trisomy 3, all cases displayed clonal structural rearrangements. Chromosomes 1 and 3 were most frequently involved in the genesis of markers. Abnormalities of chromosomes 5, 6, 9, 11 and 12 were also recurrently found, and double minutes (DM) were observed in 2 samples. Our results agree with previous findings on the preferential involvement of chromosomes 1, 3 and 6 in ovarian carcinomas, and suggest that rearrangements of certain chromosomes are non-random but are secondary to the malignant progression of these tumors.

Chromosomal abnormalities and their correlations with asbestos exposure and survival in patients with mesothelioma

Cytogenetic findings of our 30 previously reported and eight new patients with malignant pleural mesothelioma were summarised and correlated with asbestos fibre burden in lung tissue and survival. Successful cytogenetic analyses were performed on cells obtained from the tumours and/or pleural effusions of 34 of the 38 patients. Clonal chromosomal abnormalities were detected in 25 patients, 19 of them studied before treatment. Nine patients, seven of them studied before treatment, had normal karyotypes and/or non-clonal chromosomal abnormalities. Most of the karyotypic findings in the patients with clonal abnormalities were complex and heterogeneous, and no chromosome aberration specific to mesothelioma could be demonstrated. The following numerical abnormalities in decreasing order of frequency were preferentially present in karyotypic changes: -22, +7, -1, -3, -9, +11 and -14 (-/+ denoting partial or total loss or gain). Translocations and deletions involving a breakpoint at 1p11-p22 were the most frequent structural aberrations. Statistically significant correlations were found between high content of asbestos fibres in lung tissue and partial or total losses of chromosomes 1 and 4, and a breakpoint at 1p11-p22 (P = 0.0001, P = 0.003, P = 0.009, respectively). The number of copies of chromosome 7 short arms was inversely correlated with survival (P = 0.02). In this study no diagnostic cytogenetic markers of mesothelioma were found, instead the copy number of chromosome 7 short arms turned out to be a possible prognostic factor in malignant mesothelioma.

Specificity of asbestos-induced chromosomal aberrations in short-term cultured human mesothelial cells

Short-term cultured normal human mesothelial cells were exposed for 48 hours to three different asbestos compounds, crocidiolite, chrysotile, and amosite. In the concentration used (0.01 mg/ml) all three asbestiform minerals caused, within a few days, a significant increase of cells showing numerical and/or structural abnormalities. The abnormalities were analyzed in detail using banding techniques. The results were compared with the cytogenetic observations in 52 published cases of mesotheliomas. This comparison revealed only a few similarities as regards numerical deviations. The structural rearrangements in asbestos-exposed cultures, however, in many instances involved chromosome types and chromosome regions preferentially affected in mesotheliomas.